Field of the Invention
The present invention relates to a developing cartridge, a process cartridge and an image forming apparatus.
Description of the Related Art
Solid metal shafts produced through machining of steel materials have been used conventionally as metal cores of developing rollers (developer bearing members) that are utilized in image forming apparatuses; however, hollow cylindrical shaft members have been proposed (Japanese Patent Application Publication Nos. 2000-275955 and 2011-154239) in order to reduce material costs. As a configuration for rotatably supporting such cylindrical shafts on a frame, Japanese Patent Application Publication Nos. 2000-275955 and 2011-154239 disclose a configuration in which a bearing member is assembled on the inner periphery of the end of a cylindrical shaft, and the bearing member is supported on a frame, as a result of which the cylindrical shaft becomes rotatably supported on the frame.